DJ/Mix Playback Bug + Overheating & Battery Drain on Android (Pixel 8 Pro)

[JamesB_1980]

Hi all,

I wanted to report a recurring issue with the DJ/Mix feature on Android that seems to go beyond normal "bad transitions" people mention - this appears to be both a playback bug and a performance problem. I'm sharing this in case others can confirm the same experience.

1. Playback Issue: Transitions Break After 3–4 Songs

When using the DJ/Mix feature:

The first few transitions play correctly, but after around 3–4 songs, the transition suddenly goes wrong (e.g. bad timing, wrong cue point, abrupt cut, intro too early/late)

If I preview that same transition manually from the mix list, it sounds correct. So the transitions aren't "badly created." They play incorrectly only during continuous playback. This suggests the mix is fine, but the app loses sync over time while playing.

2. Performance Issues (Heat + Lag + Crashes)

My Google Pixel 8 Pro (Android) gets noticeably hot when using the Mix feature — especially when editing transitions. The app sometimes becomes sluggish and has even crashed a few times.

This phone is fairly high-spec and only 6 or so months old, and no other intensive apps cause overheating like this.

3. Battery Drain Evidence

Spotify used 73% of my battery during a DJ/Mix session. Normal music streaming usually uses around 10–20% over the same time. This suggests the Mix feature is using a lot more processing power than expected.

Why I’m Posting

I absolutely love the DJ Mix Feature. It's amazing and I'd like to help improve it, but there's a playback timing bug (transitions drift after a few tracks), and a resource/optimisation issue on Android that may be causing lag/heat which may triggers the playback bug

Would be great if others on Android could comment if they see the same behaviour.

My Setup for Reference

Device: Google Pixel 8 Pro
OS: Android 14
Background usage allowed
Adaptive Battery OFF
Issue happens on Wi-Fi and Mobile Data

If anyone else has seen the Mix feature lag, run hot, or mess up transitions after a few songs, please reply so Spotify can see it's not an isolated case.

Thanks for reading - hope this helps others compare their experience!

[JamesB_1980]

Hi All,

I've now tested the DJ/Mix feature in Offline Mode with all tracks downloaded, and I managed to get through 10 consecutive tracks with zero transition glitches. The mix stayed perfectly smooth the entire time, with none of the usual timing issues, stutters, or cue mistakes that happen in normal online use.

Why this matters:
This strongly suggests the problem isn't with the mix generation or audio files themselves. Instead, the issue appears when Spotify is running in online mode, even if the tracks are local. Going offline seems to prevent whatever background online activity is interfering with the DJ/Mix timing engine.

In other words:

The transitions only start to break when Spotify is connected to online services (e.g., background data calls, streaming checks, sync, or live session processes).
When offline, the mix runs as intended — stable, smooth, and consistent.

This gives a pretty clear direction for devs: the bug likely sits in the interaction between the Mix playback engine and Spotify's online/background processes, rather than in the mix feature itself.

I'll test again soon in Airplane Mode (fully offline, no data connection at all) to narrow this down even further. If anyone else wants to try this test and report back, it would be really helpful for confirming the behaviour across more devices.

[JamesB_1980]

Update #3 – UI Navigation Causes Audio Stutter (Even Offline)

Just another observation from me. I've noticed another pattern that might help narrow down the root cause. Even in Offline Mode, if I browse around the app while a Mix is playing e.g. switching between tracklists or scrolling through content - the audio briefly stutters or pauses.

The phone stays cool, so this doesn't seem to be thermal throttling. It feels more like a performance or threading issue, where the UI and the audio engine are competing for resources.

This suggests that part of the problem may be related to UI load affecting the playback thread, meaning the Mix playback isn't fully isolated from the app's interface rendering. Even without network activity, switching screens or loading lists is enough to interrupt the audio momentarily.

This could be connected to the timing problems seen in online mode, where extra background tasks cause even more strain.

[JamesB_1980]

Update #4 - Drift After ~20 Tracks in Offline Mode (Heat Build-Up)

A quick follow-up to my Offline Mode testing:

I managed to reach 19 tracks with no issues, but on the 20th track the transition drifted slightly. This time, the phone had become noticeably warm, even though I was still in Offline Mode.

This tells me there may be two separate performance limits affecting the Mix feature:

1. Online Mode = Early Glitches (3–4 tracks)

Likely caused by background online processes interrupting the timing of transitions.

2. Offline Mode = Much More Stable (15–20 tracks)

But after a long continuous session, the app seems to build up heat and resource usage, eventually causing a smaller timing drift.
Since no network activity was involved, this points to a resource or memory build-up over time on the device, eventually leading to heat → throttling → timing loss.

So Offline Mode avoids the early online-related glitches, but the feature still seems to run heavy on the device over long sessions.

If anyone else can test how many tracks they get through offline before any drift, it would be useful to compare results.

[JamesB_1980]

Update #5 – UI Navigation Seems to Affect Mix Stability (Even Offline)

I've noticed a further pattern that may help narrow down the cause of the playback drift. While testing in Offline Mode, the Mix stays noticeably more stable if I keep Spotify on the Now Playing screen (single track display). However, if I switch to the playlist/tracklist view or navigate around the app while the Mix is playing, the audio becomes less stable and small timing issues start to appear more quickly.

This suggests that the UI workload is affecting the audio engine, even when no network activity is involved. The Now Playing screen is relatively lightweight to render, but the playlist/tracklist view has to load more visual elements (track lists, artwork, scrolling UI, etc.), which likely increases CPU/GPU and memory usage. The result seems to be that UI rendering and audio playback are competing for resources, and the audio thread isn’t fully isolated or protected from UI load.

In simple terms, the more the app has to draw/render on screen, the more likely the Mix transitions are to drift or stutter. This could mean there's a thread prioritisation or resource contention issue within the Mix playback system.

[JamesB_1980]

Update #6 – LPF/HPF Filters Show in UI but Have No Audible Effect

I've noticed that when the Mix uses low-pass / high-pass filter sweeps, the waveform/visuals show the filter automation, but there's no audible change (no muffling for LPF, no low-end roll-off for HPF). In other words, the UI indicates the effect is active, but the audio output is unaffected.

This suggests an issue in the DSP effects chain rather than timing:

The filter node may be bypassed in the render path

The wet/dry (mix) is effectively 0% or not applied to the output bus

Automation is applied to a preview/analysis path but not the playback path

Or the effect graph isn't initialised/connected on this device/config

Because the visual sweep appears, it looks like the automation is firing, but the effect isn't reaching the audio output.

Repro: occurs whenever a transition shows an LPF/HPF sweep. Visuals change, audio does not.

Environment: Pixel 8 Pro, Android 14, Mix feature; also observed under Offline Mode and seems to be worse there.

FILTERS SEEM TO BEHAVE BETTER ONLINE THAN OFFLINE

Early observation: LPF/HPF sweeps seem more audible when Spotify is online. In Offline Mode the UI still shows the filter automation, but the audio effect is weaker or sometimes completely inaudible. This points to different audio chains for online vs offline playback. It looks like the online path initializes the DSP/effects bus correctly, while the offline path may bypass the filter node or leave its wet/dry mix at 0% until something reinitializes. I'll run a few quick checks (toggle Normalize/Equalizer, disable Crossfade/Gapless, switch outputs, and test "online first → then offline") and report back.

[JamesB_1980]

Update #7 - Most Stable Conditions Found (Car Test)

While testing the DJ/Mix feature in the car, I've found it's most stable when three things are true:

Offline playback (tracks downloaded)

Playlist view left at the top of the list

Phone screen off / dark

In this state the Mix plays flawlessly for long stretches. As soon as I wake the screen or scroll through the playlist, minor stutters or timing drift can start again.

This suggests that UI rendering and background network activity both compete with the audio engine. When the screen is dark, Spotify’s UI thread and compositor pause, freeing up resources for playback. Offline mode removes network contention, and staying at the top of the playlist keeps UI load minimal.

So the Mix engine seems to perform best when visual and network overhead are eliminated.